1. Field of the Invention
The invention is generally related to pilings on which buildings and similar housing structures are supported.
2. Description of the Prior Art
Structures of current construction include multi-level buildings weighing many tons. In some geographic areas where such structures are built, soil does not have the desired consistency to alone support the weight of such structures. In these situations, some form of foundational support must be employed to combine with the surrounding soil or substrata to provide the necessary support for such structures.
Pilings are widely known in the construction field to provide support greater than would be the case for the underlying unassisted soil. However, the support force provided by the pilings depends on two factors, the friction forces applied to the vertical walls of the piling by the surrounding soil, and the upward force applied to the bottom face of the piling by the soil (the end force). Because the friction force applied to a typical piling is much less than the requisite amount of support a structure requires, the end force must therefore supply the difference. This difference is often of substantial magnitude and thus necessitating a sectional bottom area of a correspondingly large magnitude. This results in undesirably large construction costs due, in part, to the fact that greater driving forces are required for driving pilings with larger cross sections. Typically, massive and expensive machinery is required to bore pilot holes in the soil to act as receptacles for receipt of the pilings being driven. The resulting costs, in both labor and machine time for boring such large diameter holes can be significant. There is, therefore, a need for a piling providing large support forces, while at the same time reducing the cost of implementation. The present invention meets this need.
In the field of pilings having a means for increasing the friction forces to provide enough support for erecting a structure thereon, various different embodiments of such pilings have been known for a number of years, and by way of example, forms of such embodiments can be found in U.S. Pat. Nos. 1,762,341, 4,813,816, 3,763,655, 3,222,842, and 3,432,977.
The above mentioned prior art piling apparatus have some disadvantageous features associated with them. For example, most of the apparatus mentioned require substantial machine time in order to implement the friction force mechanisms. In many of the prior art embodiments, when the piling is driven to its desired depth, an actuator member must be driven through the piling to force support platforms radially outwardly to penetrate the surrounding soil. Other such prior art apparatus utilize explosive charges to force some form of support mechanism into position. However, when the charges are detonated, a somewhat large cavity is formed, requiring the installer to fill such a cavity with cement or similar substance to maintain the integrity of the piling.
As such, it may be appreciated that there continues to be a need for a piling device which provides a large amount of support force relative to its vertical and cross sectional areas, while at the same time being cost efficient in that the machine time required to implement such a piling is relatively small. The instant invention addresses such needs.